Writing a consumer education column is an education — always for me and, I hope, for readers as well. Each week their letters and e-mails tell of new and horrifying ways they've been victimized, sometimes by travel providers and sometimes, like me, by themselves. (See item 10.) Here are some of the biggest bloopers travelers can make:

Failing to buy travel insurance: We heard from many readers after the Chilean earthquake shut down airports and the Icelandic volcano that fouled the skies and snarled travelers' plans. Those who had insurance generally came out ahead. Those who didn't and missed cruises (in the case of Chile) or were stranded (in the case of travelers to, from and in Europe) took a hit.

Buying domestic rental car insurance: You generally don't need to buy the insurance that's offered with rental cars in the U.S. (Foreign insurance is another matter.) Check your own auto insurance policy or with your credit card company to see whether you have rental coverage. If you don't need it, don't buy it.

Failing to inspect your rental car, inside and out: Make sure you and the rental company note the same damage. If it's night and dimly illuminated, insist on going somewhere you can see, or use that iPhone flashlight app (or a real flashlight, which is also helpful in unfamiliar hotel rooms). Otherwise, it will be almost impossible to prove that you didn't burn that cigarette hole in the passenger seat.

Failing to take pictures of your rental car: We've heard from several readers who received big bills for "damage" to the car they've returned, unscathed, to a European destination. You probably have a camera with you. If it has a time stamp, so much the better. Take pictures before you leave and when you return.

Forgetting that nonrefundable really means nonrefundable: Readers are often irritated when they buy a ticket and then find they can't get their money back. Usually, the least expensive ticket comes with the biggest penalties, and that means your money has said goodbye even if you haven't. You may get a credit, but you also may need to pay a huge change fee.

Thinking that cruise lines will be sympathetic to your plight: Cruise lines tend to be pretty inflexible, based on the number of complaints we get. If you miss your cruise because your airline screwed up, that's not the cruise line's problem. Ditto if your dog dies, your house burns down or any other combination of factors. If it's a big, expensive cruise, buy insurance because Murphy 's Law never takes a holiday.

Discovering that your passport is expiring the day you are leaving for Mongolia(or any other foreign destination, including Mexico and Canada): Please take a moment now to check the expiration date on your passport. Furthermore, check to see if the country you're traveling to requires at least six months remaining on your passport. And some countries require that you have a certain number of pages remaining in your passport for stamps. Check all this stuff, starting with the State Department's website at http://www.travel.state.gov.

Booking your airline ticket under the wrong name: One reader wrote to say that her sister's ticket was booked under her nun/sister's religious name, not her birth name on her passport. Under the Transportation Security Administration's Secure Flight Program, the names must match. Presumably you know your own name, but if you're booking for someone else, ask that person to look at his or her government-issued ID. Guessing is not advised.

Failing to figure in the cost of airline fees: They can add up. In the first quarter of this year, airline fees totaled $1.3 billion. One area couple got stuck with an extra $262 on fee-happy Spirit, which charged them for booking online (it also would have charged for booking by phone).

Paying cash: In 2008, I paid cash for a rental house that turned out not to exist and lost it all. Other people who were taken in by this same scam used a credit card and were protected. Even if a travel provider offers a discount for cash, don't do it. Credit card companies can be sharks, but they are good at watching out for their customers, rarely biting the hand that feeds them. Rely on them.